This invention relates generally to an apparatus and method for cold forming an L-shaped lead battery terminal.
In general, battery terminals are utilized as an interface between a sealed battery container and an external device seeking electrical power. Battery terminals are typically formed from lead in a cold or hot forming process. In a hot forming process a lead alloy is heated until it is in a molten state. The molten lead is then poured into a mold or casting and formed into a semi-finished or finished battery terminal. In the cold forming process a lead slug typically at room temperature is subjected to a number of pressing, punching and machining operations in order to create a finished battery terminal.
The hot forming process requires that the lead be heated until it reaches the molten state and then subsequently poured into a mold until it cools. A disadvantage of this method is that it requires the melting of a lead alloy to form the battery terminal. The use of melting for forming terminals may create undesirable porosity and is expensive to implement in an environmentally safe manner.
Existing methods of cold forming a standard battery terminal from a lead slug require a number of individual steps. In one method a lead slug is first modified in a preform station and then subsequently formed into a finished battery terminal in a final forming press having a split die. Alternatively, in a second method a lead slug is formed into a semi-finished battery terminal in a first station having a split die and then subsequently machined to create a finished battery terminal.
These methods of cold forming a battery terminal require a split die to form the plurality of parallel rings used to prevent movement of the battery terminal along its longitudinal axis.
The method of using a split die to form these rings results in a flash line located on the battery terminal caused by the dividing lines between the portions of the split die. This flash line can result in seepage when the battery terminal is installed in a battery.
An existing method for cold forming threads for bolts and screws entails utilizing a thread rolling head. This method allow for both axial and radial threads or designs to be cold formed on a metal rod. Typical materials cold formed utilizing this process include brass, aluminum, steel and copper.
It would be desirable to have an L-shaped battery terminal cold formed from a lead slug. It would also be desirable to cold form a battery terminal utilizing a unitary lower die without the need for a split die. It would be further desirable to have a battery terminal cold formed from a lead slug without a flash line.